Processes for the manufacture of artificial textile fibers



tion of sodium chloride Patented Jan. 11, 1944 PATENT OFF-ICE PROCESSES FOR MANUFACTURE OF ARTIFICIAL TEXTILE FIBERS Antonio Ferretti, Milan,

Italy; vested in the Alien Property Custodian No Drawing. Origina 1936, Serial No. 96,470. plication July 31, 1940 Italy August 28, 1935 9 Claims.

This invention concerns improvements in or relating to processes for the manufacture of artificial textile fibers.

In co-pending U. S. patent application Serial No. 96,470 of 1936, processes are described and claimed by which a casein and a colloidal solution thereof may be produced from milk and by which the colloidal solution can be spun and coagulated in a manner which is suitable for use in the manufacture of artificial textile fibers. Coagulated fibers produced by these processes must be rendered insoluble and the present invention provides in a process for the manufacture of artificial textile fibers the step of rendering casein fibers insoluble by subjecting them to treatment in a solution of which formaldehyde forms the basic substance-together with sodium chloride. Said application 96,470 was filed August 1'7, 1936 corresponding to application filed in Italy August 28, 1935; and the present application is a division thereof. The casein substance, as from milk, is maturated in aqueous alkaline solution while diluted to spinnable viscosity, and then in the next stage spun into a multiplicity of fine, delicate, water-containing filaments which are received and coagulated in an acid bath containing a. salt or salts, as aluminum sulfate. These weak and vulnerable filaments then require to betreated to render permanent fibers of them,

larly relates.-

It is to be understood'that, as .described in the co-pending patent application, the term casein fibers refers to fibers made from casein solution alone or of a mixture thereof with cellulosic vis- 35 cose.

It is known that casein is hardened by formaldehyde but the coagulated fibers contain a condehyde could have rendered them insoluble. For

this reason it has not been possible to obtain pliable and successful artificial textile fibers by known means. According to the present invention, however, the coas ated fibers are hardened in an aqueous solution orwmcn formaldehyde forms the basic substance together with the addih v which prevents further swelling of the fibers.

The fibers may be treated'with solutions, of

which formaldehyde forms the basic substance also with the addition of sodium chloride,.and aluminium salts, or an acid.

1 application August 17,

Divided and this ap- Serial No..348,991. In

An aqueous solution of sodium chloride of less than exercises a swelling action on the casein fibers whilst a solution with more than 10% exercises an astringent action. It is therefore very useful I to regulate the behaviourof the fibers in the bath which renders them insoluble by employing an adjusted quantity of sodium chloride.

It is possible to operate with a solutionhaving' but one concentration only, for instance, with 90 parts of a 12% aqueous solution of sodium chloride and 10 parts of 40% formaldehyde, to which aluminium salts maybe added or not. Examples of suitable aluminium salts are ,potassium alum, aluminium chloride and aluminium sulphate. It is preferable, however, and even very important, to operate with various solutions having progressively increasing concentrations, and to begin the treatment of the filaments with weak concentrations, for instance with 99 parts of 12% aqueous solution of sodium chloride and 1 part of 40% formaldehyde, gradually passing to higher concentrations. The procedure is the same when aluminium salts are ,added, but it is preferable not to reduce thesodium chloride concentration below 10% in order to avoid an excessive and undesirable swelling of the fibers.

The solution for rendering the filaments insoluble which are prepared in the manner de- 0 scribed above may be slightly acidified, preferably with sulphuric acid.

According to a preferred embodiment of the present invention the fibers are rendered partially insoluble and are maintained under tension in an initial lowconcentration bath, in order e to prevent shrinkage thereof, and subjected to further treatment 'in baths of higher concentra-" tion after being cut to a desired length in order 40 to obtain. a twisting thereof.

The fibers may also be. rendered insoluble by treatment in an initial low.,concentration bath and by subsequent treatment in a series of baths of gradually increasing concentration. ,By the Present process the weak filaments, fresh from the acid coagulating bath, are promptly treated in-an aqueous bath containing a salt, such as sodium chloride, which functions to regulate and prevent excessive swelling, and consequent 5 tendency toredissolution of the filaments, pending the gradual insolubilizing action of the formaldehyde, which agent is the basic element relied as described, is of impractical inferiority without so the characteristic modifying actions recited.

on m rendering insoluble the filament but which,

States Letters Patent is:

1. In a process for manufacture of artificial textile fibers from casein-containing substance,

and following the stage of spinning a multiplic-' ity of fine filaments from a maturated and diluted alkaline solution thereof and coagulating such filaments in an acid bath; the after-stage of rendering such filaments into permanent fibers characterized by the following steps: promptly treating the weak water-containing filaments from the coagulating bath in an aqueous bath containing both formaldehyde for insolubilizing functions and sodium chloride to prevent undue swelling before insolubilizing is completed; and comprising about 90 parts of a sodium chloride solution of about to 12 percent strength and about 10 parts of' a formaldehyde solution of about 40 percent concentration.

2. In a process for the manufacture of artificial textile fibersrom casein-containing substance, and 'foll'owing'th'e stage of spinning a multiplicity of ime filaments from a dilute maturated alkaline solution thereof and coagulating such filaments in an acid bath; the afterstage of rendering such water-containing filaments into permanent fibers by first treating the filaments in. a sodium chloride aqueous bath which fortifiesthe vulnerable filaments against injurious swelling, and later treating them in an aqueous bath of formaldehyde of concentration to insolubilize the, filaments.

3. A process as in claim 2 and'wherein in the filament treatingstage the successive baths contain' formaldehyde in progressively increasing concentration' 4. In a process for manufacturing artificial textile fibers from an alkaline solution of casein spun asdelicate filaments inan acid bath, thestage, following theresulting acid coagulation, comprising the step of treating the coagulated filaments in at least one aqueous bath in which sodium chloride has been dissolved, and thereafter in aseparate-bath rendering the filaments insoluble with formaldehyde.

5. A-process'as per claim 4', in which at least one salt chosen fromthe group consisting of the soluble salts ofaluminum, is added to at least one of said sodium chloride baths.

6. In a process for manufacturing artificial textile fibers from an alkaline solution of casein spun in acid bathsfthe stage, following the acid coagulation, comprising treating the coagulated filaments in at least two successive aqueous formaldehyde baths in which sodium chloride has been dissolved, and characterized in that at least soluble salts of aluminum, is added to at least one of the baths of the treatment following the acid. coagulation of the filaments.

7. In a process for the manufacture of artifi- ,cial textile fibers from casein-containing substance, and following the stage of spinning a multiplicity of fine filaments from a diluted and maturated alkaline solution thereof and coagulating such filaments in an acid bath; the afterstage of rendering such filaments into permanent fibers comprising insolubilizing the filaments by formaldehyde, and characterized by promptly treating the weak water-containing filaments from the coagulating bath in an aqueous bath containing sodium chloride adapted to regulate and restrain swelling and tendency to re.- dissolution of the filaments pending the insolubilizing action of the formaldehyde.

8. In a process for the manufacture of artificial textile fibers from casein-containing substance, and following the stage of spinning a multiplicity of fine filaments from a diluted and maturated alkaline solution thereof and coagulating such filaments in an acid bath; the afterstage of rendering such filaments into permanent fibers by steps comprising insolubilizing the filaments by formaldehyde, and characterized by promptly treating the weak water-containing filaments from the coagulating bath in an aqueous bath which contains sodium chloride to re- Q strain swelling and prevent redissolution oi the filaments pending the insolubilizing action of the formaldehyde, and containing also an aluminum salt to act asan astringent or hardening agent.

9. In a process for the manufacture of artificial'textile fibers from casein-containing substance, and following thestage of spinning a multiplicity of fine filaments from a diluted and maturated alkaline solution thereof and coagu lating such filaments in an acid bath; the afterstage of rendering such filaments into permanent fibers by treatments comprising insolubilizing the filaments by formaldehyde, and characterized by promptly treating the water-containing filaments from the coagulating bath in an aqueous bath containing sodium chloride adapted to restrain swelling of the filaments, and then treating them in at least two additional baths, with progressive increase of formaldehyde concentration in the successive baths; whereby the insolubilization of the filaments is maintained gradual and its completion is delayed to follow safely the restraint of swelling thereof.

ANTONIO FERRE'I'I'I. 

